'\" et
.TH MKFIFO "1P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
mkfifo
\(em make FIFO special files
.SH SYNOPSIS
.LP
.nf
mkfifo \fB[\fR-m \fImode\fB] \fIfile\fR...
.fi
.SH DESCRIPTION
The
.IR mkfifo
utility shall create the FIFO special files specified by the operands,
in the order specified.
.P
For each
.IR file
operand, the
.IR mkfifo
utility shall perform actions equivalent to the
\fImkfifo\fR()
function defined in the System Interfaces volume of POSIX.1\(hy2017, called with the following arguments:
.IP " 1." 4
The
.IR file
operand is used as the
.IR path
argument.
.IP " 2." 4
The value of the bitwise-inclusive OR of S_IRUSR, S_IWUSR, S_IRGRP,
S_IWGRP, S_IROTH, and S_IWOTH is used as the
.IR mode
argument. (If the
.BR \-m
option is specified, the value of the
\fImkfifo\fR()
.IR mode
argument is unspecified, but the FIFO shall at no time have permissions
less restrictive than the
.BR \-m
.IR mode
option-argument.)
.SH OPTIONS
The
.IR mkfifo
utility shall conform to the Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 12.2" ", " "Utility Syntax Guidelines".
.P
The following option shall be supported:
.IP "\fB\-m\ \fImode\fR" 10
Set the file permission bits of the newly-created FIFO to the specified
.IR mode
value. The
.IR mode
option-argument shall be the same as the
.IR mode
operand defined for the
.IR chmod
utility. In the
.IR symbolic_mode
strings, the
.IR op
characters
.BR '\(pl' 
and
.BR '\-' 
shall be interpreted relative to an assumed initial mode of
.IR a =\c
.IR rw .
.SH OPERANDS
The following operand shall be supported:
.IP "\fIfile\fR" 10
A pathname of the FIFO special file to be created.
.SH STDIN
Not used.
.SH "INPUT FILES"
None.
.SH "ENVIRONMENT VARIABLES"
The following environment variables shall affect the execution of
.IR mkfifo :
.IP "\fILANG\fP" 10
Provide a default value for the internationalization variables that are
unset or null. (See the Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 8.2" ", " "Internationalization Variables"
for the precedence of internationalization variables used to determine
the values of locale categories.)
.IP "\fILC_ALL\fP" 10
If set to a non-empty string value, override the values of all the
other internationalization variables.
.IP "\fILC_CTYPE\fP" 10
Determine the locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as opposed to
multi-byte characters in arguments).
.IP "\fILC_MESSAGES\fP" 10
.br
Determine the locale that should be used to affect the format and
contents of diagnostic messages written to standard error.
.IP "\fINLSPATH\fP" 10
Determine the location of message catalogs for the processing of
.IR LC_MESSAGES .
.SH "ASYNCHRONOUS EVENTS"
Default.
.SH STDOUT
Not used.
.SH STDERR
The standard error shall be used only for diagnostic messages.
.SH "OUTPUT FILES"
None.
.SH "EXTENDED DESCRIPTION"
None.
.SH "EXIT STATUS"
The following exit values shall be returned:
.IP "\00" 6
All the specified FIFO special files were created successfully.
.IP >0 6
An error occurred.
.SH "CONSEQUENCES OF ERRORS"
Default.
.LP
.IR "The following sections are informative."
.SH "APPLICATION USAGE"
None.
.SH EXAMPLES
None.
.SH RATIONALE
This utility was added to permit shell applications to create FIFO
special files.
.P
The
.BR \-m
option was added to control the file mode, for consistency with the
similar functionality provided by the
.IR mkdir
utility.
.P
Early proposals included a
.BR \-p
option similar to the
.IR mkdir
.BR \-p
option that created intermediate directories leading up to the FIFO
specified by the final component. This was removed because it is not
commonly needed and is not common practice with similar utilities.
.P
The functionality of
.IR mkfifo
is described substantially through a reference to the
\fImkfifo\fR()
function in the System Interfaces volume of POSIX.1\(hy2017. For example, by default, the mode of the FIFO
file is affected by the file mode creation mask in accordance with the
specified behavior of the
\fImkfifo\fR()
function. In this way, there is less duplication of effort required for
describing details of the file creation.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIchmod\fR\^",
.IR "\fIumask\fR\^"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "Chapter 8" ", " "Environment Variables",
.IR "Section 12.2" ", " "Utility Syntax Guidelines"
.P
The System Interfaces volume of POSIX.1\(hy2017,
.IR "\fImkfifo\fR\^(\|)"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
